On Tue, Mar 25, 2025 at 11:46 AM Miklos Szeredi <mszeredi@xxxxxxxxxx> wrote:
>
> Allow the "verity" mount option to be used with "userxattr" data-only
> layer(s).
>
> Previous patches made sure that with "userxattr" metacopy only works in the
> lower -> data scenario.
>
> In this scenario the lower (metadata) layer must be secured against
> tampering, in which case the verity checksums contained in this layer can
> ensure integrity of data even in the case of an untrusted data layer.
>
> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
> ---
> fs/overlayfs/params.c | 11 +++--------
> 1 file changed, 3 insertions(+), 8 deletions(-)
>
> diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
> index 54468b2b0fba..8ac0997dca13 100644
> --- a/fs/overlayfs/params.c
> +++ b/fs/overlayfs/params.c
> @@ -846,8 +846,8 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
> config->uuid = OVL_UUID_NULL;
> }
>
> - /* Resolve verity -> metacopy dependency */
> - if (config->verity_mode && !config->metacopy) {
> + /* Resolve verity -> metacopy dependency (unless used with userxattr) */
> + if (config->verity_mode && !config->metacopy && !config->userxattr) {
This is very un-intuitive to me.
Why do we need to keep the dependency verity -> metacopy with trusted xattrs?
Anyway, I'd like an ACK from composefs guys on this change.
Thanks,
Amir.
